A drive device of the type described above is known from the publication “Vakuum-Leistungsschalter—ein neuer Weg im Bereich der Mittelspannung” [Vacuum power breakers—a new option in the medium-voltage range], Sachsenwerk, March 1982, pp. 11 et seq.
In the disconnected state of the contact parts, the movable contact part is connected in a force-free manner to the pendulum-type lever by being mounted centrally such that it can pivot, whereas the pendulum-type lever is itself, on the one hand, connected to the housing of the interrupter by means of an external pivot bearing and, on the other hand, is connected, by means of an internal pivot bearing lying opposite the external pivot bearing, to the contact spring which is mounted at both ends such that it can pivot. The other free end of the contact spring is connected to the central pivot bearing of a three-point lever, which is likewise mounted such that it can pivot on the housing of the interrupter and whose other external pivot bearing is under the controlling influence of the plastic switching rod.
The connected state of the contact parts is achieved by the three-point lever being pivoted by means of the switching rod in the clockwise direction in the region of its external bearing such that the contact spring is positioned approximately parallel to the direction of action of the contact pressure force, and thus the switching rod is in practice no longer subjected to the contact pressure force. The contact pressure force therefore now only acts on the movable contact part of the interrupter.
Readjustments or alterations to the contact pressure forces are not provided for here and cannot be carried out without a considerable degree of installation complexity.